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Does the Universe Have Higher Dimensions? Part 1
- imvetri 6y agoStep 1: Every dimension has an observer. Step 2: "An observer watches something" happens in Zero dimension, Step 3: "An observer watching an observer" happens in One dimension, Step 4: "An observer watching an observer watching an observer" happens in Two dimension, . . . . . Step n: it can go on till the n dimension. Let's twist the rule to itself. An observer (zero dimension) An observer watching itself, (one dimension) An observer watching itself observing, (two dimension) An observer watching itself observing itself, (three dimension) An observer watching itself observing itself,.................. (n dimension) And there can be any level of observer, so there can be any level of dimensions.
- goldenkey 6y agoStep 5. The longer the buffering, the greater the sneeze.
- uniqueid 6y agoCan someone who knows more physics than I tell me if the question is even meaningful? My naive assumption is that we'd have as many dimensions as there are distinct things (atoms, I suppose).
- Borrible 6y agoThat implies there ARE distinct things, doesn't it?
- uniqueid 6y ago'Distinct in some context', I guess. Eg: a person could take a photograph of clouds in the sky and come up with list of rules to categorize them into a number of discrete clouds.
- Borrible 6y agoDon't take my comment too seriously, although it is based on serious speculation and thought. I only wanted to refer on the one hand to the philosophical or at least linguistic problem, what a 'thing' is and the possibility of the unification to one field of the, up to now still multiform, thing in the quantum field theory we call Universe. Just a mind game. Or not... ;-) What is meant in the article is that one needs currently 11 coordinates in a mathematical space which is supposed to be a mapping of our physical reality to describe a point in it.
- deleted 6y ago[deleted]
- jpeanuts 6y agoNot at all serious but... maybe all electrons have the same mass, charge, etc. because there is only one electron, bouncing backwards and forwards through time. As it passes backwards we see it as the anti-electron (positron). When they meet they annihilate from our perspective, but that's just the electron being reflected and becoming a positron heading backwards. To be clear this is all not at all consistent with observations - just a fun(?) thought experiment.
- Borrible 6y agohttps://en.m.wikipedia.org/wiki/One-electron_universe https://en.m.wikipedia.org/wiki/One-electron_universe
- jstanley 6y agoOut of interest, what observations is this not consistent with?
- magicalhippo 6y agoThe argument against is summarized in the Wikipedia article. Basically it is this: We measure electrons in different places all the time. Due to the speed of light it can't instantly move from A to B, so for this to actually be one electron it would have to travel back in time to be at some place at the right time. However, an electron traveling back in time would appear as a positron, so if that what was going on we should be seeing a fairly equal number of positrons as we do electrons, as the one electron rushes around to appear as an electron where it needs to. Except we don't, electrons outnumber positrons by a huge margin.
- bostonpete 6y ago> However, an electron traveling back in time would appear as a positron, so if that what was going on we should be seeing a fairly equal number of positrons as we do electrons, as the one electron rushes around to appear as an electron where it needs to. What about this part of the article though...? "According to Feynman he raised this issue with Wheeler, who speculated that the missing positrons might be hidden within protons."
- SubiculumCode 6y agoare you saying: what if dimensions are not discrete, but fields.?
- Borrible 6y agoAh, no no no. Oh, God, what have I done!? What I wanted to indicate was firstly, as a physical speculation the possibility of a universal field in the sense of the quantum field theory, which shows additional dimensionality with breaking of its symmetry in hierarchical levels and thus there is in a certain sense only one thing, the universal field. Secondly, the question when something is considered as an independent 'thing', which is a philosophical question. Third, the question of the interpretation of the relation of mathematical apparatus and reality. What does the dimensionality of the mathematical model mean? A scientific-theoretical question. And the gluons of this all are just linguistics and semantics. ;-)))
- compressedgas 6y agoThat is what is called by the name of degrees of freedom. The dimensions of space-time are to the degrees of freedom as the basis vectors of a coordinate system are to the homogeneous matrix. Or something like that.
- ithkuil 6y agoPerhaps what you mean is the dimensionality of hilbert space
- monkeycantype 6y agoDo I know more physics than you? Problynot. But he’s my attempt to explain how I understood the article: We experience a universe with 3 spatial dimensions, if we imagine an axis through space, there are two other axes orthogonal to the first axis and to each other, that an object can move on any of the axes independently, without moving in any of the others. We can’t add a fourth axis, there is no fourth line we can choose along which an object can move without also moving in at least one other dimension - or at least that is our experience. We also know from seeing 2d shadows of 3D objects, that a higher dimensional object can be projected into lower dimensions. We can twist an object and see changes in a shadow that make perfect sense if we know the shadow is a 2d projection of a rotating 3D object. There are features of our universe that make sense if we think about the universe as a 3D shadow of a higher dimension system. So what does that mean? Are higher dimensional models a nice math trick, or do the models work because they describe the true higher dimensional nature of the universe, that we experience as a lower dimensional projection. Ok time to pass the baton who can take this deeper.
- lgl 6y agoGood answer, a 4th dimension and the shadow projection analogy is brilliantly exemplified by Carl Sagan in this popular video: https://www.youtube.com/watch?v=UnURElCzGc0 https://www.youtube.com/watch?v=UnURElCzGc0
- travisjungroth 6y agoI think it's also the most important analogy, more than things like a 2D being meeting a 3D being. The goal of these physics models is to better explain the world. It's a hint that a model is better when it simplifies things (not that the model itself is necessarily simple). Think of the crazy things astronomers drew to explain the paths of the planets in the sky with the Earth in the center and circular orbits. But what if the Sun is in the center and the orbits are ellipses? Things are way easier. Same thing happens if you look at the projection of a cube. It looks like chaos. But if you are aware of a third dimension, it all makes a lot of sense.
- m12k 6y ago
- toolslive 6y agoYou don't need to know more physics. If you see something (a particle fe) disappear, and reappear somewhere else then a possible explanation is that it got there via another dimension. So if you eliminate all other possible explanations, the only remaining one is that there must be more dimensions. However, since things appearing and disappearing does not happen on macroscopic scale, the dimensions must be small.
- gtt 6y agoSo this is how UFOs move!
- bArray 6y ago> Can someone who knows more physics than I tell me if the question is even meaningful? Any new physical property could potentially be exploited to improve some existing idea. The discovery of the electromagnetic force eventually gave way to WiFi and 5G. The discovery of the quantum realm for example has yielded the concept of quantum computing. If we can discover high dimensions, we can eventually interact with them and use them.
- wombat23 6y agoIn this context, the dimensions are the degrees of freedom that a particle can move in. I think it becomes meaningful when you consider the metric (ie. definition of distances) and the laws of nature inside that space, and if additional dimensions help in formulating more phenomena with a less complex system of equations. -> Classically, there are 3 spatial dimensions (directions of movement) with Euclidean metric, and all the classical laws (Newton's laws, gravity, etc.). Quite successful, but breaking down in extreme cases (high energy, ie. velocity/mass/etc). +there is a whole range of seemingly unrelated laws necessary. -> with relativity theory (both special and general), time becomes a 4th dimension, but it has a special status in the metric (opposed sign), making spacetime non-Euclidean. One effect of this is suddenly you don't need a law of gravity anymore. Things just follow geodesics in this space. It also explains some effects that could not be derived from classical gravity. Essentially explaining more phenomena with less "overhead", in exchange for more dimensions.
- hcrean 6y agoThere are certain proofs of the dimensionality of space at different scales. The equipartition theorem details that thermal energy is divided down by degrees of freedom. In higher dimensional space there are different ratios of translations to rotations, so observations of the triple state diagrams of diatomic vs monatomic molecules would diverge from observation. The time it takes spheres to settle after falling into a square container is a function of the dimensionality of the container. Observations as we scale real experiments with steel ball bearings suggest that the balls can't move in any other dimensions. In higher dimensional space the great geodesics are longer, we would expect a deviation in the relativistic corrections to the GPS system that we don't observe. The interesting question however is at the largest scales. The universe might have much higher dimensions, we just happen to be in a relatively "compact" part of it...
- jiggawatts 6y agoAdditional tiny "curled up" dimensions wouldn't have such direct macroscopic effects. Atoms would be many trillions of times the size of the extra dimensions
- selimthegrim 6y agoHeat capacity of deuterium and ortho/para hydrogen too (if spin would be affected)
- alkonaut 6y agoWhat trips me up (but the article glosses over) is the concept of "the size of a dimension". How are dimensions larger and smaller? To me, a dimension is usually something you measure in. My height is my extent in the vertical diredction (if standing up). What would it mean for that dimension to be small? Our 3 spatial dimensions I assume are "large", meaning what? The axes extend to some apparent infinity without repeating? Does a "small" dimension behave like a longitude, that after a certain while it repeats itself? So the two dimensions of a sphere surface are "smaller" than the 2 dimensions of an infinite plane, is that how to interpret the small/large? So [the surface of] an infinitely long but finitely thick cylinder would have one large (along) and one small (around) dimension? Is "small" then always finite, but large can be large-but-finite or inifinte?
- codethief 6y ago> So an infinitely long but finitely thick cylinder would have one large (along) and one small (around) dimension? Exactly. The mathematical concept behind this is the idea of compactness[0, 1]. A compact manifold always has finite volume. In the same way, a compact dimension always has finite length and this is what is meant here.[2] Note that the converse does not hold: Not every dimension of finite length is necessarily compact. (The mathematical reason being that the metric tensor could become smaller and smaller ("fade out") towards the infinite ends.) But for the purposes of talking about string theory, you can usually equate the terms "finite length/volume" and "compact". > Is "small" then always finite, but large can be large-but-finite or inifinte? Yes, "small" is always finite (compact). As for "large" dimensions, I would say that's a matter of terminology and physicists tend to not be very precise with their terminology. It can both be large-but-finite (compact) or infinite (non-compact), depending on the context. [0]: https://en.wikipedia.org/wiki/Compact_space https://en.wikipedia.org/wiki/Compact_space [1]: https://mathworld.wolfram.com/CompactManifold.html https://mathworld.wolfram.com/CompactManifold.html [2]: This is also what string theorists mean when they "compactify a dimension": They take this infinite dimension and "wrap it around" a circle (of a given circumference) and end up with a cylinder or some more complicated object (depending on what they started with).
- chartpath 6y ago
- k__ 6y agoDoesn't the holographic principle state that the universe is actually 2D?
- sohkamyung 6y agoMaybe this by the same author may help answer your question. [1] [1] https://backreaction.blogspot.com/2021/03/is-universe-really-hologram.html https://backreaction.blogspot.com/2021/03/is-universe-really...
- jcranmer 6y agoThe holographic principle arises basically from two facts: * The AdS/CFT correspondence, which states briefly that a universe having properties our universe doesn't have is mathematically equivalent do a different universe with one fewer dimension and different properties our universe also doesn't have. This is the most celebrated result in string theory, by the way. * The entropy of a black hole is proportional to its surface area, not its volume. From these two results, one can speculatively extrapolate that the information density of the universe uses one fewer than dimension than the actual interaction volume we experience, and this extrapolation is the holographic principle.
- im3w1l 6y ago> The entropy of a black hole is proportional to its surface area, not its volume. Does the following argument hold? The Schwarzschild radius of a black hole is proportional to the mass. So the surface area is proportional to M^2. How can bigger holes store ever more entropy per unit mass?
- teekert 6y agoSo... where is Part 2? I can't find it... Edit: Ah the content is 2 days old, it will come. In any case: Great content!
- ineedasername 6y agoIf there were an infinite number of dimensions, would that mean there was also a path, if we could find it, from any point in 3d space to any other point in 3d space that was of arbitrary length?
- pas 6y agoIn general no unless there's one that's warped just the right way. Which is unlikely. (Also it comes down to cardinality of the involved infinities. If we have countably many infinite dimensions but uncountably many points in each one of them, then you have a "lot more" point-point pairs than dimensions.)
- caf 6y agoAdditional dimensions don't give you additional ways to be closer to something, they give you additional ways to be further away. If we're displaced from each other by X, Y and Z units along axes in the usual 3 spatial dimensions, the closest we can be is if we're at a coincident position in each of the additional dimensions. Any displacement along those additional axes just moves us further away from each other.